Decalins

Abstract

Decalins of the formula ##STR1## wherein ring A is aromatic or a trans-1,4-disubstituted cyclohexane ring; R 2 is methyl, --CH 2 R', --OR', --CO--R', --CN, --COOH, --CO--OR', --CO--SR' or --O--CO--R'; R 1 is hydrogen, methyl, --CH 2 R, --OR or --CH 2 OR, or when R 2 is methyl, --CH 2 R', --OR' or --CO--R', R 1 also can be --CN, --COOH, --CO--OR, --CO--SR or --O--CO--R; R and R' each are alkyl; and R 1 and R 2 each have up to 12 carbon atoms and together have at most 14 carbon atoms, their racemates and optically active antipodes, are described. Liquid crystalline mixtures comprising Compound I as well as their use in electro-optical devices also are disclosed.

We claim: 
     
       1. A compound of the formula ##STR47## wherein R 1  is hydrogen, methyl, --CH 2  R, --OR or --CH 2  OR, R is alkyl; and R 1  has up to 12 carbon atoms, its racemates or its optically active antipodes.   
     
     
       2. The compound of claim 1, wherein R is straight-chain alkyl. 
     
     
       3. The compound of claim 1 wherein R 1  is methyl, --CH 2  R or --OR. 
     
     
       4. The compound of claim 3, wherein R 1  is methyl or --CH 2  R. 
     
     
       5. The compound of claim 1 wherein R 1  has at most 9 carbon atoms. 
     
     
       6. The compound of claim 5 wherein R 1  has at most 7 carbon atoms. 
     
     
       7. The compound of claim 1 wherein R 1  is propyl, butyl, pentyl or heptyl. 
     
     
       8. The compound of claim 1 in racemic form. 
     
     
       9. An electro-optical cell containing a compound of the formula ##STR48## wherein R 1  is hydrogen, methyl, --CH 2  R, --OR or --CH 2  OR, R is alkyl; and R 1  has up to 12 carbon atoms, its racemates or its optically active antipodes.   
     
     
       10. A liquid crystalline mixture comprising at least two compounds at least one being a compound of the formula ##STR49## wherein R 1  is hydrogen, methyl, --CH 2  R, --OR or --CH 2  OR, R is alkyl; and R 1  has up to 12 carbon atoms, its racemates or its optically active antipodes.   
     
     
       11. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR50## wherein R 23  is straight-chain alkyl or alkoxy of 2 to 7 carbon atoms. 
     
     
       12. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR51## wherein R 24  is straight-chain alkyl of 3 to 7 carbon atoms. 
     
     
       13. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR52## wherein R 24  is straight-chain alkyl of 3 to 7 carbon atoms. 
     
     
       14. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR53## wherein R 24  is straight-chain alkyl of 3 to 7 carbon atoms. 
     
     
       15. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR54## wherein R 25  is straight-chain alkyl of 2 to 7 carbon atoms. 
     
     
       16. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR55## wherein R 24  is straight-chain alkyl of 3 to 7 carbon atoms and R 26  is cyano or straight-chain alkoxy of 1 to 3 carbon atoms. 
     
     
       17. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR56## wherein R 25  is straight-chain alkyl of 2 to 7 carbon atoms. 
     
     
       18. The liquid crystalline mixture of claim 10 comprising a compound of the formula ##STR57## wherein R 25  is straight-chain alkyl of 2 to 7 carbon atoms.